A scintillator provided in a scintillator panel or a radiation detector preferably includes columnar crystals. The scintillator including a columnar crystal has both a function of converting radiation into fluorescence (e.g. visible light) and a function of transmitting generated light (i.e. acting as a light guide).
That is, the columnar crystal acts as a transmission path of the converted light. Thus, there are some technical proposals for enhancing the light guide effect by providing a layer of the columnar crystals having a small diameter on a side close to a substrate of the scintillator. When the layer of the columnar crystals having a small diameter is provided on the side close to the substrate of the scintillator, it is possible to suppress a disorder of crystal orientation in the vicinity of the substrate.
However, suppressing a disorder of crystal orientation has not been considered on a top side of the layer of columnar crystals having a small diameter. When the disorder of crystal orientation is large on the top side of the layer of the columnar crystals having a small diameter, there may be coalescence between adjacent columnar crystals, which blocks or scatters the transmission of light, and induces the degradation of resolution characteristics. That is, it may be difficult to improve the light guide effect, when the disorder of crystal orientation is enlarged on the top side of the layer of columnar crystals having a small diameter. Thus, there has been a demand for developing a scintillator capable of improving the light guide effect.